Rebecca Cabage/Invision/AP/Shutterstock Michael Bublé
"We're really trying to be present with the pregnancy because, most likely, it's the last time," the singer tells PEOPLE. "I want it to be really special for [Luisana], and I know it goes really fast. Since it's probably the last one, I just want to make sure that we're really enjoying every second of it."
Bublé, 46, first revealed that he and his wife are expecting another baby in his music video for "I'll Never Not Love You," which premiered in February.
In the video, Bublé and Lopilato, 34, recreate some of the most romantic scenes in cinematic history, including iconic sequences from movies like The Notebook, Love Actually and Titanic. At the end, Bublé is brought back to reality where he is met by his wife — who reveals her baby bump — and their three kids: Noah, 8, Elias, 6, and Vida, 3.
Throughout Lopilato's pregnancy, Bublé says he's made sure his wife knows "that she can depend on me."
"She just kind of points her finger and says, 'Go do this, go do that,' " he says. "I love that. I love taking care of her."
Just as excited as Bublé and Lopilato about the new baby are their kids, who have already started weighing in on names.
"If it's a little boy, my boys want to name him after themselves, which doesn't work," he says with a laugh. "If it's a girl, my daughter has decided that Snowy for Snow White is what the girl would be named. I think we need help."
Ahead of baby No. 4's arrival, Bublé is keeping busy performing his Las Vegas residency (which is currently running through May 7) and promoting his women's fragrance, By Invitation, now available at Walgreens.
"This is going to sound sentimental, but, obviously, fragrance is something that's always been huge to all of us," he says. "It's a sense that takes us right back. I remember being a kid and, every Christmas, I would go to The Body Shop and buy my grandmother White Musk. I'd save up for it, and she would wear it all year. When she passed away, I would still go to the store every year, and I would buy it. It would make me think about her. Fragrance is a funny thing."
When he created his own fragrance By Invitation back in 2016, Bublé says his wife played a big part.
"I don't care what I do, whether it's music or film or perfume, I always go to my wife," he says. "She has such a great sense of taste, and she's such a classy woman. When I wrote 'I'll Never Not Love You,' as a matter of fact, the first person who ever heard it was her. She's always my barometer as to what's good, because she just has such a great, unique sense of style."
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Bublé says he "can't even tell you how many times" he's smelled his fragrance randomly while out and about.
"What's even funnier, this is the truth, I've gotten into elevators, or I've sat across someone at a restaurant, and I've smelled it, and I've genuinely liked it," he says. "I've genuinely made a comment to someone and said, 'Oh, I really love that. What is that fragrance?' And they've gone, 'It's you.' It's funny, actually, my sister wore it once and I had no idea. I just thought it was beautiful. I was like, 'What have you got? That's great.' "
While the fragrance has been largely popular amongst women, Bublé wanted it to appeal to all people.
"When I was creating this, I wanted it to be something that could be worn by both men and women, even though I know it's bought mostly by women," he says. "I do like that I could wear it. It wouldn't be overpowering. It's just subtle and quite beautiful with the patchouli and the vanilla."
Bublé has come a long way since his days in high school wearing Calvin Klein's Obsession For Men fragrance.
"I wore as much as I possibly could," he says with a laugh. "I think our high school probably smelled so badly — or so good. I'm not sure which one. I think all of us were wearing far too much. I think we thought the more, the better. Those hallways just smelled like every kind of perfume you could find."
"I also remember Joop," he adds. "I had a friend that wore Joop. And he wore so much Joop, I would just be like, 'Oh my God.' "
Richard Dobson/Newspix via Getty Michael Buble
At his Vegas residency, Bublé has been in good company: the other night, he says he hung out with Lady Gaga, who just completed a residency of her own on May 1.
"I went to go see her show and her residency," he says. "She was just amazing. It made me really proud to know that she and I can be part of continuing the legacy of this music that we love so much. We stand on the shoulders of our heroes. We talked about Tony [Bennett] and Frank [Sinatra] and Dean [Martin] and all those guys. I said to her, 'You know, I love the respect that you show Tony and others. One day, when we're that age, hopefully, people will have that same kind of reverence for us.'"
"I think both of us take it seriously, being custodians of that art," he continues. "She made me so proud. She's such a great, beautiful person."
After Vegas, Bublé will head abroad for his international tour, where he's hoping his family can join him on some dates.
"I've tried to schedule the tour around Luisana's movies," he says. "She does two or three films a year. She actually just filmed a movie while pregnant, and I would go back and forth with the kids to set. I know how much she loves it. Because I know how much I love it. Here in Vegas, I came off stage the other night, and there they are sitting at the side of the stage."
These days, the afterparty is pretty G-rated.
"We go watch Encanto for the 97th million time," he says.